Many people are aware that old engine oil shouldn't be dumped, but recycled.

Regardless, up to 100 million litres (approximately 26.4 million US gallons) of the stuff is improperly disposed of each year in Australia alone, according to the Department of the Environment, Water, Heritage and the Arts.

It's dumped in household trash, used as weed killer, pour in ditches, left laying about or illegally dumped. Actually, I'm feeling rather guilty as I write this as I have a gallon or so of old sump oil stashed away.

Used engine oil is incredibly toxic stuff and a gallon can contaminate one million gallons of water. Pouring it on land doesn't reduce the risk either as it can seep down into the water table as well as rendering the soil incapable of sustaining plant life.

Used oil doesn't wear out - it just gets filthy. It can be cleaned of contaminants and recycled continuously. It can even be cleaned to the point where it can be reused as engine oil.

The dirty oil goes through the same refining process as oil that is extracted from wells. New engine oil made from recycled oil meets the standards used in the industry lubrication industry. According to the American Petroleum Institute, re-refined oil is of as high a quality as a virgin oil product.

The recycling process is as follows:

- Removal of any water
- Filtering to remove solids and additives
- De-asphalting to remove bituminous content
- Distillation

Environmental benefits of recycling used engine oil

Information from the USA Environmental Protection Agency states that re-refining used oil takes only about one-third the energy of refining crude oil to lubricant quality. It takes 42 gallons of crude oil, but only one gallon of used oil to produce a half gallon of new, high-quality lubricating oil that can be used in car engines.

Other uses for recycled engine oil

While the following uses may not be all that "green", it goes to show just how important that this resource is recycled rather than just thrown out. By recycling engine oil, we reduce the need for extraction of crude oil and the associated environmental impacts of that activity.

- Engine oil can also be used as fuel oil. By recycling just two gallons of used oil, it has the energy potential to generate enough electricity to run the average household for almost 24 hours. One gallon of used oil processed for fuel contains about 140,000 British Thermal Units (BTUs) of energy. 

- It can be reused as hydraulic oil

- Many petro-chemical based products can be made with it

Where to recycle engine oil

To find out where you can recycle engine oil in the USA, try Earth911.org and search for a collection center via zip code.

In Australia, for further information on used oil and to find your nearest used oil collection facility, contact oilrecycling@environment.gov.au or call 1800 982 006

If you're in Canada, try the Used Oil Recycling site for information on collection points.

For folks in the UK, visit Oil Bank Line.

Equally as important as recycling engine oil is to buy products made from the stuff. After learning more about it, I'd have no hesitation in using recycled engine oil it in my car as long as it was certified as meeting industry standards.